There have been a number of incidences of herbicide drift onto cotton crops this season. In this weeks Web on Wednesday we speak to Mike Beeston, Senior Grower Services Manager with Cotton Australia about the extent of the problem and some new label changes to 24-D products. We talk to Dr Greg Constable, CSIRO about how 2,4-D products affect the cotton plant and we speak to Bruce Pyke, CRDC about 2,4-D resistant cotton and why it hasn’t been progressed.

Mike Beeston, Senior Grower Services Manager - Cotton Australia, Greg Constable - CSIRO and Bruce Pyke - CRDC comment on the instances of herbicide drift on cotton crops this season, changes to the 2,4-D label, how these products damage the plant and the fate of 2,4-D tolerant cotton.

Mike Beeston, Senior Grower Services Manager, Cotton Australia.

Mike we have been hearing some reports of herbicide drift particularly hormone products. Your team usually is the first to find out about these, can you tell us the extent this year?

There have been reports of extensive damage already in Central Queensland and that’s continuing to appear. Also across the Darling Downs there are numerous hits there and we are hearing of more minor exposure levels in the other areas around the Macintyre, the Gwydir, the Namoi, the Macquarie districts and out at Walgett as well.

This season there have been changes to the label of 2,4-D products. Can you tell me about those changes?

They are interim changes at the moment. The products are still under review with the APVMA and to date the APVMA are putting stickers on each and every drum that’s sold. They dictate that you must apply with coarse to very coarse droplet spectrums and a minimum wind speed of 3km per hour and a maximum of 15km per hour.

You mentioned droplet specifications; can you go into a bit more detail about how people will be achieving these?

The current setup of most booms won’t achieve the course to very course droplet spectrum that’s now required as per the label directions so for your general flat fans (11002’s etc) there not going to cut it so the applicators have got to refer to manufacturers specifications. Anyone who sells nozzles will have the charts for the particular manufacturers and/ or refer to spray application specialists who are also out there and willing to help people set up their spray rigs.

In the interim, how can cotton growers work with their neighbours to try and prevent this from happening?

I think that in the short term at least the best thing that growers can do is make the district or their neighbours aware that there is cotton in the ground. We have seen quite often that people just didn’t realise there was a cotton crop nearby and so by just distributing maps or ringing up the neighbour and making them aware that there are cotton crops in the ground and to be careful of what’s going on.

The process of the review of these products has been going on for some time, Cotton Australia and the Australian Cotton Industry Council have had involvement in that. Can you give us some comments on some of the history?

It has been going for a couple of years now and Peter Cone from Cotton Australia is right at the forefront working on behalf of the industry with the APVMA. To date we have put in a lengthy submission as have a number of the cotton grower associations as well. To date we have asked for about 10 things to be included on labels and we have only had a couple of them included far. So there are still opportunities and we are still in there working hard at it.

Greg Constable, CSIRO Plant Industry.

We are having a discussion about 2,4-D damage in cotton. Can you start by talking about how these products actually affect cotton?

2,4-D mimics natural hormones in the plants and it creates this rapid growth, particularly and obviously in young growing tissue. That tends to be negative to a plant, in fact fatal in some circumstances. Cotton, soybeans and grapes to my knowledge are highly sensitive to this and that’s the reason why we often talk about it in cotton because these chemicals are widely used as broadleaf weed control in dryland industries.

What is the product fate in the plant. Is it broken down, is it used?

It is sort of used up in the symptoms that you see on the plant, that is the result of the action of the very small amount of that product that is in the plant due to drift in most cases. So it is used up in the action that it creates.

If a grower has been affected by 2,4-D drift from any source. Should they manage their crop any different than what they would if they didn’t get drifted on?

I know of no data that would indicate some action you can take to minimise or reduce that damage. There are plenty of people around with experience trying to do that so I would stick to first principles and look after the crop according to its requirements. So if it is a small crop then it would need management for what a small crop needs and to follow those principles accordingly.

So just do the best for what the crop needs in the same way as what you do anyway?

You do your best for what it is, so if it is a really heavy damage situation, the plants aren’t going to grow and it might be a situation of walking away from them. The more common thing with it is damage that is not so uniform in a field and minor damage in most of the field. In these cases the plants will recover, usually with some yield damage, but they will subsequently start producing crop.

Bruce Pyke, Cotton Research and Development Corporation.

The Australian cotton industry and particularly CSIRO has undertaken work in developing 2,4-D resistant or tolerant cotton. Can you give us some background?

About 10 years ago, CSIRO started doing some work on looking at the possibility of incorporating 2,4-D tolerance or resistance into cotton. They were able to do that with the technology that was available at the time and they had plants in the field that were then tested and shown to have a degree of tolerance. So in affect, taking cotton from a very highly sensitive plant to one that was only moderately sensitive; capable of withstanding low to moderate levels of drift.

How effective it was at the time and what happened after that?

At the time it was not seen to be as high priority for development as the insect tolerance through the BT genes that we have seen, so the effort was put into that. The other issue for CSIRO is that they didn’t have complete ownership of some components of that technology, so they had been able to test the concept but in terms of commercialisation, a couple of additional agreements would have to be put in place before it could go ahead. That is an additional problem in developing it and probably one of the things that contributed to it not being pursued at the time.

In recent years this issue had obviously come to a head again and I believe that ACGRA initiated a meeting to discuss whether it needs revisiting again. You were involved in facilitating that process. Can you give us an update on some of the issues that came out of that meeting and the outcome?

Back in about mid September (2005), ACGRA brought together a group of people representing a broad cross section the industry including growers, consultants and researchers to talk about the issue; ‘was it worth reconsidering developing the 24-D tolerance into cotton as a means addressing the problems we have seen in recent years with 24-D drift?: to make cotton a bit more tolerant so that it became less of a problem for the industry.

That was the starting point. CRDC and the Cotton CRC helped facilitate the forum. We asked some of the key researchers like Greg Constable (CSIRO) and Graham Charles (NSW DPI) who had been involved with the original work to give presentations. There was quite a healthy and robust discussion about the pros and cons of going down the track of developing the technology and in the end we asked everyone to give us their individual and collective feedback on what we should do.
About 30 people gave us feedback on the day and more than ½ of those were growers from right across the industry. The response was overwhelming; about 85% responded that it wasn’t worth pursuing the technology for a whole range of reasons. Only a couple of people present on the day felt that after they had heard everything they would have considered it was still worth pursuing. So there was a fairly strong vote to not proceed with a technology like this.

Obviously the pros and cons would have been discussing pretty heavily. Can you tell us about what some of the cons were that convinced people that it shouldn’t be pursued?

There is a whole range of things really but partly the lack of clarity of the commercial pathway for CSIRO. The fact that by putting this into commercial varieties, it would probably have to be put into all varieties and made available right across the industry otherwise you would have cotton out there that someone might assume was tolerant and it wasn’t. So it would create a whole stack of problems like that.

The fact that it is probably not sending the right message; if we have got drift problems still going on, there are ways that those things can be addressed through industry leadership both in the cotton and the grains industries. You would have to questions whether that fully happened yet and that leads onto a whole range of potential extension and training issues that could be pursued and perhaps even stricter labelling. On the labelling, the APVMA have been doing a review of 2,4-D and that’s lead to some changes with labels and those were aimed at trying and reduce the drift problem. If we don’t see that reduce this year then there is going to be further pressure potentially on the registration of products like that. Going back to looking at 2,4-D tolerance in cotton, it will take five or six years to put it into current varieties, and in five or six years time we may not have access to products like 2,4-D. There is a degree of uncertainty there.

There is also the public perception issue. If the onus would come directly on the cotton industry as a public perception, the current public feeling about herbicide tolerant crops is not as good as it is for perhaps insect tolerant crops, simply because there is a perception out there that herbicide tolerant crops mean more use of herbicides and greater reliance on herbicides. It’s sending the wrong message out there.

On the positive side though, in terms of praise for developing 2,4-D tolerance, it was seen to be a potentially very good means of protecting growers interests and crops from those situations where drift does occur. I guess we all accept it. In our variable climate it is difficult to control everything but, it was seen to be something of an insurance policy and the aim was not to use 2,4-D products on a cotton crop as we currently use with glyphosate on glyphosate tolerant cotton.

Some of the other issues that were raised against the technology were things like the fact that this work was done about 10 years ago and some of the technology was, in today’s terms, considered a bit old. There may well be better technology available but it would have to be developed now.

There was an issue of what message does it send out there to have crops that we are saying ‘well its okay if they get hit by drift there now that we’re able to cope with it’. It’s not really addressing the best management practices issue across all farming sectors.

One of the other problems was the fact that by putting a new trait in our varieties we are possibly diverting some of our attention away from other important issues that we need to deal with like improving yield, quality and disease tolerance.

So, there was a whole combination of things that I think convinced most of the people that attended this forum that it really wasn’t worthwhile pursuing this 2,4-D tolerance and that the industry was probably better off looking at issues such as developing good relationships between cotton and the grains industry for example, and encouraging some industry leadership on adopting and putting best management practices for spray application in the place and perhaps some additional support for education and training. Those sorts of things were seen to be some of the positives that we should be pursuing with a bit more vigour.

Further Information: David Kelly